An efficient approach for treating composition-dependent diffusion within organic particles
Abstract
Mounting evidence demonstrates that under certain conditions the rate of component partitioning between the gas and particle phase in atmospheric organic aerosol is limited by particle-phase diffusion. To date, however, particle-phase diffusion has not been incorporated into regional atmospheric models. An analytical rather than numerical solution to diffusion through organic particulate matter is desirable because of its comparatively small computational expense in regional models. Current analytical models assume diffusion to be independent of composition and therefore use a constant diffusion coefficient. To realistically model diffusion, however, it should be composition-dependent (e.g. due to the partitioning of components that plasticise, vitrify or solidify). This study assesses the modelling capability of an analytical solution to diffusion corrected to account for composition dependence against a numerical solution. Results show reasonable agreement when the gas-phase saturation ratio of a partitioning component is constant and particle-phase diffusion limits partitioning rate (<10% discrepancy in estimated radius change). However, when the saturation ratio of the partitioning component varies, a generally applicable correction cannot be found, indicating that existing methodologies are incapable of deriving a general solution. Until such time as a general solution is found, caution should be given to sensitivity studies that assume constant diffusivity. Furthermore,more »
- Authors:
-
[1];
[2];
- Univ. of Manchester, Manchester (United Kingdom)
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Publication Date:
- Research Org.:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Org.:
- USDOE
- OSTI Identifier:
- 1393748
- Report Number(s):
- PNNL-SA-122836
Journal ID: ISSN 1680-7324; KP1701000
- Grant/Contract Number:
- AC05-76RL01830
- Resource Type:
- Accepted Manuscript
- Journal Name:
- Atmospheric Chemistry and Physics (Online)
- Additional Journal Information:
- Journal Name: Atmospheric Chemistry and Physics (Online); Journal Volume: 17; Journal Issue: 17; Journal ID: ISSN 1680-7324
- Publisher:
- European Geosciences Union
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 54 ENVIRONMENTAL SCIENCES
Citation Formats
O'Meara, Simon, Topping, David O., Zaveri, Rahul A., and McFiggans, Gordon. An efficient approach for treating composition-dependent diffusion within organic particles. United States: N. p., 2017.
Web. doi:10.5194/acp-17-10477-2017.
O'Meara, Simon, Topping, David O., Zaveri, Rahul A., & McFiggans, Gordon. An efficient approach for treating composition-dependent diffusion within organic particles. United States. doi:10.5194/acp-17-10477-2017.
O'Meara, Simon, Topping, David O., Zaveri, Rahul A., and McFiggans, Gordon. Thu .
"An efficient approach for treating composition-dependent diffusion within organic particles". United States. doi:10.5194/acp-17-10477-2017. https://www.osti.gov/servlets/purl/1393748.
@article{osti_1393748,
title = {An efficient approach for treating composition-dependent diffusion within organic particles},
author = {O'Meara, Simon and Topping, David O. and Zaveri, Rahul A. and McFiggans, Gordon},
abstractNote = {Mounting evidence demonstrates that under certain conditions the rate of component partitioning between the gas and particle phase in atmospheric organic aerosol is limited by particle-phase diffusion. To date, however, particle-phase diffusion has not been incorporated into regional atmospheric models. An analytical rather than numerical solution to diffusion through organic particulate matter is desirable because of its comparatively small computational expense in regional models. Current analytical models assume diffusion to be independent of composition and therefore use a constant diffusion coefficient. To realistically model diffusion, however, it should be composition-dependent (e.g. due to the partitioning of components that plasticise, vitrify or solidify). This study assesses the modelling capability of an analytical solution to diffusion corrected to account for composition dependence against a numerical solution. Results show reasonable agreement when the gas-phase saturation ratio of a partitioning component is constant and particle-phase diffusion limits partitioning rate (<10% discrepancy in estimated radius change). However, when the saturation ratio of the partitioning component varies, a generally applicable correction cannot be found, indicating that existing methodologies are incapable of deriving a general solution. Until such time as a general solution is found, caution should be given to sensitivity studies that assume constant diffusivity. Furthermore, the correction was implemented in the polydisperse, multi-process Model for Simulating Aerosol Interactions and Chemistry (MOSAIC) and is used to illustrate how the evolution of number size distribution may be accelerated by condensation of a plasticising component onto viscous organic particles.},
doi = {10.5194/acp-17-10477-2017},
journal = {Atmospheric Chemistry and Physics (Online)},
number = 17,
volume = 17,
place = {United States},
year = {2017},
month = {9}
}
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